{"id":16418,"date":"2024-03-05T00:46:40","date_gmt":"2024-03-05T00:46:40","guid":{"rendered":"https:\/\/shareperformanceinsight.com\/index.php\/2024\/03\/05\/ancient-star-dune-evidence-isnt-missing-its-been-hiding-in-plain-sight-radar-reveals\/"},"modified":"2024-03-05T00:46:40","modified_gmt":"2024-03-05T00:46:40","slug":"ancient-star-dune-evidence-isnt-missing-its-been-hiding-in-plain-sight-radar-reveals","status":"publish","type":"post","link":"https:\/\/shareperformanceinsight.com\/index.php\/2024\/03\/05\/ancient-star-dune-evidence-isnt-missing-its-been-hiding-in-plain-sight-radar-reveals\/","title":{"rendered":"Ancient \u2018star dune\u2019 evidence isn\u2019t missing. It\u2019s been hiding in plain sight, radar reveals"},"content":{"rendered":"
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Across sweeping desert vistas, spectacular star dunes stand out. The distinctive mounds are among the tallest sand dunes on Earth, and their pyramid shapes are sculpted by a crossfire of winds gusting from multiple directions, creating spiraling sand ridges that pinwheel outward from a central peak. <\/p>\n

While star dunes are commonly found in sandy deserts worldwide, scientists have long wondered about their formation and their puzzling absence in the geological record. <\/p>\n

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Related article<\/span> Rare rock structures could provide a glimpse into possible life on ancient Mars<\/span> <\/p>\n<\/div>\n

Now, an investigation of a star dune\u00a0in Erg Chebbi, a region of the Sahara Desert in Morocco,\u00a0has revealed surprises about its age and growth \u2014 and hinted that ancient evidence of star dunes may have been hiding in plain sight all along. <\/p>\n

Using radar scans and analysis of sand grains buried deep inside the star dune, scientists mapped the mound\u2019s internal structure. The researchers calculated that the oldest part of the dune\u2019s base\u00a0formed around 13,000 years ago. But for about 8,000 years, the research team discovered, the star dune \u2014 which covers 0.4 miles (700 meters) and stands 328 feet (100 meters) tall \u2014 didn\u2019t grow much at all. In fact, most of the growth to its present size\u00a0took place over the past 1,000 years, much more rapidly than expected, researchers reported March 4 in the journal Scientific Reports. <\/p>\n

The new study\u2019s scans also revealed that the dune was on the move. <\/p>\n

\u201cKnowing how fast these things are moving is quite important for infrastructure in these areas,\u201d as their migration could affect construction of roads or pipelines, he added. <\/p>\n

Below the surface<\/h3>\n

When these radio waves\u00a0bounced back to the receiver\u2019s antenna, they produced high-resolution images showing the shapes of different sediment layers below the researchers\u2019 feet, Bristow explained. <\/p>\n

The next step was to collect sand samples at different depths to find out when those sands were deposited. To do that, the scientists extracted tubes of sand cores from Lala Lallia by digging a shallow pit and hammering hollow pipes made of metal or plastic into the dune \u201cso we end up with these little tubes of sand inside an opaque container,\u201d Duller said. In the lab, the researchers\u00a0then peered inside individual sand grain crystals of quartz and feldspar\u00a0to measure environmental radiation that accumulated over thousands of years in the dune\u2019s dark depths. <\/p>\n

\u201cThere\u2019s radioactivity everywhere, at very low levels,\u201d Duller said. \u201cSome of it gets stored within the crystals.\u201d <\/p>\n

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Related article<\/span> A shallow lake in Canada could point to the origin of life on Earth<\/span> <\/p>\n<\/div>\n

Exposure to daylight scrubs radiation from these crystal reservoirs within 10 to 30 seconds, he added. But once sand grains are buried, radiation from the environment around them starts building up. In the laboratory at Aberystwyth, the scientists made the collected\u00a0grains release their stored energy as light, then analyzed light intensity to calculate their age, a technique called optically stimulated luminescence dating. The researchers shined a light on the minerals to free trapped electrons, producing a luminescent signal that the researchers then measured to determine how long the crystals had been in darkness. <\/p>\n

\u201cThe brighter the light, the older the sediment,\u201d Duller explained. By measuring the brightness\u00a0of grains from different depths in the dune, the research team was\u00a0\u00a0able to calculate when\u00a0the structure first formed, when it had its biggest growth spurt, and its rate of movement. <\/p>\n

A mystery solved<\/h3>\n

The new\u00a0findings also addressed a longstanding mystery for geologists: Where is all the ancient evidence of star dunes? <\/p>\n

Desert environments are typically well-preserved in the geological record, and dunes leave behind clues about their distant past in layers of compressed sandstone. But ancient evidence of star dunes is\u00a0exceptionally rare, save for one known example in Scotland dating to the Permian-Triassic (about 251.9 million years ago). <\/p>\n

\u201cWhy is that? Where have all the star dunes gone?\u201d Duller asked. The answer, the scientists wrote, may be a matter of perspective. Star dunes are so big; perhaps eroded parts of their preserved structures were previously identified as standalone remnants of other types of dunes, the study authors reported. <\/p>\n

\u201cWhen you look at each piece individually of a star dune in the geological record, it\u2019s going to look like something else,\u201d Duller said. \u201cBut when you get all of these pieces together \u2014 and you can see these large troughs of cross-bedded sands in the middle, you can see these arms stretching out in each direction \u2014 that\u2019s when you can confidently say it\u2019s a star dune.\u201d <\/p>\n

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Related article<\/span> Scientists offer evidence to support possible Great Sphinx origin story<\/span> <\/p>\n<\/div>\n

One possible explanation for why ancient star dunes were overlooked for so long \u00a0is that, for a long time, it was unknown just how common they were, Goudie suggested. <\/p>\n

\u201cThe fact that star dunes have not been identified very much in the stratigraphic record may partly be because many geologists were not very much aware of star dunes and only knew about longitudinal dunes and barchans (crescent-shaped dunes),\u201d Goudie said. \u201cNow, with the help of Google Earth, we know just how widespread these features are.\u201d <\/p>\n

Mindy Weisberger is a science writer and media producer whose work has appeared in Live Science, Scientific American and How It Works magazine.<\/em><\/p>\n\n

This post appeared first on cnn.com<\/div>\n<\/div>","protected":false},"excerpt":{"rendered":"

Across sweeping desert vistas, spectacular star dunes stand out. The distinctive mounds are among the tallest sand dunes on Earth, and their pyramid shapes are sculpted by a crossfire of winds gusting from multiple directions, creating spiraling sand ridges that pinwheel outward from a central peak. While star dunes are commonly found in sandy deserts <\/p>\n","protected":false},"author":0,"featured_media":16419,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[23],"tags":[],"class_list":{"0":"post-16418","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-world"},"_links":{"self":[{"href":"https:\/\/shareperformanceinsight.com\/index.php\/wp-json\/wp\/v2\/posts\/16418","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/shareperformanceinsight.com\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/shareperformanceinsight.com\/index.php\/wp-json\/wp\/v2\/types\/post"}],"replies":[{"embeddable":true,"href":"https:\/\/shareperformanceinsight.com\/index.php\/wp-json\/wp\/v2\/comments?post=16418"}],"version-history":[{"count":0,"href":"https:\/\/shareperformanceinsight.com\/index.php\/wp-json\/wp\/v2\/posts\/16418\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/shareperformanceinsight.com\/index.php\/wp-json\/wp\/v2\/media\/16419"}],"wp:attachment":[{"href":"https:\/\/shareperformanceinsight.com\/index.php\/wp-json\/wp\/v2\/media?parent=16418"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/shareperformanceinsight.com\/index.php\/wp-json\/wp\/v2\/categories?post=16418"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/shareperformanceinsight.com\/index.php\/wp-json\/wp\/v2\/tags?post=16418"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}